This invention relates to a screen printing apparatus for providing a pattern of conductor strips on circuit board blanks. The apparatus has a receiving frame provided with a screen printing nest for the circuit board blank to support the same in a planar manner. The screen printing nest may be exposed to vacuum at those sides which are oriented away from the circuit board blank.
In the manufacture of circuit boards for producing multilayer circuits, particularly on unfired (green) ceramic films which undergo sintering at low temperatures, conductor patterns are printed with an electrically conductive paste on the green circuit board blanks. Such a process is described in an article by J.I. Steinberg, S.J. Horowitz and R.J. Bacher, entitled "Herstellen yon Mehrlagenschaltungen mit niedrig sinternden grunen Keramikfolien" ("Manufacture of Multilayer Circuits with Green Ceramic Films Undergoing Sintering at Low Temperatures") in the periodical "Elektronikproduktion & Pruftechnik", Issue 9A of 1986. According to this article, the screen printing apparatus utilizes a screen printing nest serving as the backup support for the green ceramic film and is provided with a plurality of small holes through which vacuum is applied to immobilize the green ceramic film. Care has to be taken that the holes in the screen printing nest should be sufficiently small so that the outline of the holes will not be reproduced on the printed side of the film. In observing such a requirement, the manufacture of printing screen nests involves significant expense. In case pass-through contacts are to be provided, where very small tolerances have to be observed, risks are high that the underlying hole in the screen printing nest will be soiled.